The Sawyer® Water Filters feature a 0.1 Micron Absolute Hollow Fiber Membrane, which uses medical technology developed from kidney dialysis. When the water is drawn through the filter, it flows through the side walls of the Hollow Fiber tubes. Sediment, bacteria, protozoa, cysts, and other contaminants are filtered out exceeding all applicable EPA recommendations. NO CHEMICALS, NO WAITING, NO PUMPING, NO WORRIES!Biological Filtration: Highest level of biological filtration available in the portable water filters category for removal of bacteria, E. coli, Giardia, and Cryptosporidium.Removal rates: 7 Log Bacteria 99.99999%, 6 Log Protozoa & Cysts 99.9999%